US996311A - Die-head of screwing-machines. - Google Patents

Description

T. & T. P. GHATWIN & J. VIRTUE.V

DIE HEAD 0F SGREWING MACHINES. APPJJOA'HON FILED MAB. 23,`1910.

996,311. Patenteagunezv, 1911.

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DIE HEAD or SCREWING'MAGHINBS.

APPLIUATION FILED MAR. 23. 1910.

Patented June 27, 1911.

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4 SHEETS-SH ma; T.A P. CHATWIN & J. VIRTUEL DIE HEAD OP SGEBWING MACHINES. APPLICATION FILED MAB. 23, 1910.

996,81 1 Patented June 2'?, 1911.

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T. & T. P. CHATWIN '&`J. VIRTUE.

DIE HEAD 0F SGREWING MAGHINES.

APPLICATION FILED MAB. 23` 1910.

Patented June 2'?, 1911.

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THOMAS CI-IATWIN, THOMAS PHILIP CI-IATWIN, AND JAMES VIRTUE, 0F BIRMINGHAM, ENGLAND.

DIE-HEAD 0F SCREWINGr-MACHINES.

Specification of Letters Patent.

Application filed March 23, 1910.

Patented June 27, 1911. Serial No. 551,154.

To all whom it may concern:

Be it known that we, THOMAS CHA'rWIN, engineers-tool manufacturer, and THOMAS PHILIP CHATWIN, engineer, citizens of Great Britain, and residents of Great Tindal street, Birmingham, in the county of Warwick, England, and JAMES VIRTUE, citizen of Great Britain, and resident of 253 Maryvale road, Bournville, Birmingham, county of lVarwick, England, draftsman, have invented certain new and useful Improvements in and Relating to Die-Heads of Screwing-Machines, of which the following is a specification. I

This invention comprises improvements m and relating to die heads of screwing machines, and has for its object the provision of an improved device for releasing the dies in such heads without stopping the machine.

The invention consists in the application of a spring so mounted as to cause the cam controlling the dies to over-run the spindle and die head to a degree limited by adjustable devices to close the dies onto the work in conjunction with a brake for retarding the cam so that the spindle and die head can overtake it, thus causing the dies to run out ofl3 the work, when desired, without stopping the machine.

We are aware that a spring has been used for rotating a cam ring when a control device worked by contact with the work has been released for the purpose of ope-ning dies of screwing machines and also that a brake has been used in conjunction with aJ spring but in this prior case the brake was applied to compress the spring and'close the dies so that the cam ring could be locked in this position by a pawl. When the pawl was released the spring expanded to open the dies. In our invention we are particularly desirous of avoiding such use of spring for opening the dies as it is found in practice not to be dependable.

On the appended drawings Figure l is a central vertical section through a die head of a screwing machine with the invention applied. Fig. 2. is a transverse section on line 2--2 of Fig. 1. Fig. 8. is a transverse section taken on line 3-3 of Fig. 1 in direction of the arrow a. Fig. 4t is a similar section on line 3--3 but looking in the direction of arrow b. Fig. 5 is a sectional view showing a brake actuating device. Fig. 6. shows one method of automatically operating the actuating device. Fig. 7. is a view looking toward the back of the die head showing a catch that may be used. Fig. 8 is a plan thereof. Fig. 9 is a. perspective view of al form of brake band used in the device of our invent-ion.

These drawings show, a method of carrying the invention into practice as applied to a screwing machine having a die setting and releasing cam and chaser type dies. In this case we provide the back of the die head A with a coned or stepped slot al concentric with the axis thereof and extending through about 120 to 140 degrees of the circle of the head, and we arrange a sliding block B in this slot provided with two locking pins b1 b2 so that the block may be set fast at any desired position in the slot. The adjusting and releasing cam C which is of the well known scroll form having four eccentric die engaging faces c1 giving variations in the closing or opening of the dies D we provide with an annular recess c2 in the side toward the back of the die head andA into this recess projects a portion b3 of the locking pin b2 previously mentioned which portion project-s beyond the head of the pin.

The sliding block B has within it a concentric slot b4 or recess and the earn C is equipped with a pin or peg c3 passing through the annular recess c2 in the back into this slot b4 in the sliding block of the die head see Fig. t. A suitable spring E is arranged in the recess c2 in the cam, one end c1 engaging the projection b3 on the locking pin b2 and the other e2 engaging the pin c3 on the cam C so that a tension is set up between the cam and the adjustable block and as the latter is set fast to the die head the screwing spindle also. As the cam pin 03 is free in the slot b4 in the sliding block B this spring E keeps the pin c3 in the end of the slot farthest removed from the locking pin b2 to the projection b3 of which the other end c1 of the spring is connected. This position for the cam corresponds to the closed position for the dies, but it is obviously adjustable to suit requirements owing to the arrangement for the alteration of the position of the sliding block to allow for any adjustment of the dies within the capacity of the scrolls of the cam. It will thus be seen that, due to the slot b4 in the sliding block B engaged by the cam pin c3 the cam C is free to rotate quite independently of the die head A and in a contrary direction, for a distance equal to the length of the slot in the block, but this rotation opposes the tension of the spring E and immediately the force effecting it is removed, the cam rotates forward again to the original position with its pin at the end of the slot as above stated. This rotation of the cam C contrary to the die head and against the tendency of its spring isvreally simply relative movement between the two caused by retarding the cam and thus allowing the die head to overtake it. This is effected by a brake applied to the cam during its rotation with the die head and spindle, causing it to lose speed with respectto the latter so that the die head passes it and puts the spring E in greater tension. This relative partial back rotation of the cam in respect to the spindle runs the dies D back up the scrolls c1 of the cam C and so oif the work they are screwing. When the dies are required in screwing position again, the retarding infiuence or brake is removed from the cam C and its spring E forces it to overrun the spindle and die head A for the length of the slot b4 of the sliding block B thus closing the dies D by the action of its scrolls 01. As will be seen both these actions are carried out without stopping the machine.

The form of brake may be suited to circumstances but we here show a band brake F encircling the cam C and having lugs at each end; one f1 rests on a fixed step f2 and the other f3 is operated by a screw pin f4 to tighten the brake around the periphery of the cam C.

A further arrangement for applying the brake F is shown at Fig. 5, which is more readily accessible for operation and more rapid in its action than the previous arrangement. In this case a bearing G is secured to the bed and has a short rod g1 working in it. The rod g1 has a thread at g2 passing through a fixed nut g3 and at its eXtremity g4 engages the lug f3 of the brake around the cam. An offset g5 forms a hand part for rotating the rod which by coaction of its thread g2 with nut g8, reciprocates in the bearing G and applies the desired force t-o lug f3 of the brake. With this arrangement an automatic operation of the brake, and consequently of the dies, can readily be obtained. In such a case the rod g1 carries a pinion g and the bearing G is provided with a passage way for a rod I-I provided with a rack 71,1, see Fig. 6. The rod II has a spring if bearing against the bearing G and a collar 7b3 at the other end has a notched portion 7b4 engaged by'a pivoted gravity or spring catch h5. The rod J projects from the machine saddle and works through the guide gi in the bearing G carrying tappets j1 and jg. l

As shown at Fig. 6 the tappet j2 is just striking the end of catch h5 to release the rod I-I which by action of its spring h2 moves farther through bearing G, its rack h1 driving pinion g and advancing the rod g1 to apply the brake and allow the cam to bring the dies into open position. On the reverse or return travel of the saddle the rod .I returns and tappet j1 engages the end of rod H and forces it backward again rotating pinion gG thus retreating rod g1 and releasing brake. The rod II is driven against its spring by the tappet jl and is pushed through bearing G until the notched part it* is engaged by the catch h5 thus retaining the spring in tension.

It will be seen that the tappet j1 prevents the screwing machine saddle from being withdrawn more than a certain distance from the die head and dies, so that by putting the work to be screwed into the vice, so that it just comes flush with the front of the dies, any desired length of thread within the range of the mechanism may be screwed over and over again. Moreover the dies are re-set to size automatically without any movement on the part of the operator being necessary other than withdrawing the screwing machine saddle. Y l

In this device the opening or releasing of the dies is entirely mechanical e'. e. it is performed by the engine or motor or other power which is driving the machine, and is not done by a spring or springs. One spring only is used7 and that is to turn the cam back to the set or closed position after t-he dies have been opened or released, so that this spring is only subject to the lightest of work. Y

The overhang of the die head from the main bearing of the machine is very greatly reduced by the before mentioned device, which is obviously a great advantage, as the bed of the screwing machine can be shortened accordingly, or if the length of the bed remains the same the eXtra space available allows the saddle or vice increased travel and so increases the capacity ofthe machine.

Left hand threads can be screwed by removing the right hand cam and substituting one of the opposite hand, which operation can be carried out in a few minutes. No other alteration or addition to the machine is necessary except of course the left hand screwing dies.

In this device the opening or releasing of the dies is really instantaneous, no time being lost through t-he operation of special releasing cams or trip gears.

It may be desirable to provide a catch over the cam pin o3 to avoid any possibility of the dies running back whenV the machine is at work on heavy screwing. Such a catch is shown at Figs. 7 and 8 in which a bracket K is provided with a boss in which a spring plunger 701 is arranged. The plunger is provided wjith inclined faces 7a2 7c3 for engaging in a shaped notch in the cam pin. When the dies are closed and screwing the plunger engages the pin and holds it in the end of the slot remote from the fixed peg '62. lVhen the brake is applied to the cam and the die head overtakes it the plunger is carried over the pin so that the dies may open.

What we claim and desire to secure by Letters Patent is l. A die head construction :tor screw machines comprising in combination, a rotary die head provided with an adjustable stop device having a slot therein, dies radially movable in said head toward and away from the work, a cam element provided with scroll cam portions for operating said dies and having a pin projecting into said device slot, a spring connected with said cam element and device for shifting the dies to a working position, and a brake device acting on the cam element to cause suiicient differential movement between the cam and head so as to retract the dies from the work.

2. A die head construction for screw machines comprising in combination, a rotary die head, dies radially movable thereon t0- ward and away from the work, a cam element provided with scroll cam portions for shifting said dies, a spring connected with said cam and head to normally advance the dies toward the work, a device adjustably mounted on the head for connection of one end of the spring thereto, means anchoring said devi-ce in adjusted position, and a brake device acting on the cam to cause sutcient relative movement between the cam and head to retract the dies from the work.

3. A die head construction for screw ma- Chines comprising in combination, a rotary die head, dies radially movable toward and away from the work, an element provided with means for shifting the dies, a spring connected with said element and head to normally advance the dies toward the work, said head having a segmental slot therein, a block in said slot forming a connection for one end of said spring to said head, means for anchoring said block in said slot, and a brake device acting on said element to cause suiiicient relative movement between the element and head to retract the dies from the work.

4. A die head construction for screw machines comprising in combination, a rotary die head, dies radially movable therein toward and away from the work, a cam element provided with scroll cam portions for shifting said dies, a spring connecting said cam and head to normally cause the dies to advance toward the work, a catch device for retaining the parts in such working position, and a brake device acting on the cam to cause suiiicient relative movement between the cam and head to retract the dies from the work.

5. A die head construction for screw machines comprising in combination, a rotary die head, dies radially movable toward and away from the work, a cam element provided with scroll cam portions for shifting said dies, a spring connecting said cam and head to normally cause the dies to advance toward the work, a releasable catch for holding the parts in such working position, and a brake device for causing sufficient relative movement between the cam and head to retract the dies from the work.

6. A die head construction for screw machines comprising in combination, a rotary die head provided with a slotted portion, an adjustable stop device in such slotted portion and provided with a slot therein, dies radially movable in said head toward and away from the work, a cam element provided with scroll cam portions for shifting said dies and having a pin projecting into .the slot in said stop device, a spring connected with the pin of said cam element and said stop device for shifting the dies toward a working position, and a brake mechanism for causing suiicient relative movement of the cam element and head to retract the dies Jfrom the work.

7. A die head construction comprising in combination, a rotary die head provided with an adjustable stop and spring holding device, dies radially movable on said head, a cam-like element connected with said dies for shifting the same and provided with a projection engaging said stop device, a spring connected with said stop device and said cam element to normally cause the dies to advance toward the work, and braking means for causing suiiicient relative movement between the head and cam element to retract the dies from the work.

In testimony wherof we aiiiX our signatures in presence of two witnesses.

THOMAS CHATWIN. THOMAS PHILIP CHATWIN. JAMES VIRTUE.

Witnesses:

F. GILBERT BRETTELL, J. BEAUMONT PERCIVAL.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C.

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